feat: IMAP mail sync with thread-to-contact matching (PRD §6.1)

Real IMAP connection via imapflow library:
- Connects to IMAP server (IMAPFlow, TLS on port 993)
- Fetches recent messages (configurable limit, default 20)
- Extracts: from, fromEmail, subject, date, snippet (200 chars)
- Thread-to-contact matching (PRD §6.1):
  1. Match sender email against persons table
  2. If no person match, extract domain and match against company.website
  3. Returns matchedCompany + matchedPerson for each email
- Audit-logged (action: crm.mailsync:imap)
- Zod validated (host, port, user, password, folder, limit)
- 502 on IMAP connection failure with detail
- 400 on validation failure

Tested: invalid creds → 502 'IMAP connection failed', missing host → 400

skills/aminer-daily-paper/prompts/enrich.md

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+# Paper Enrichment Prompt
+
+You are enriching academic papers with Chinese content before they are sent as Feishu cards.
+
+For each paper in the `papers` array that is missing a Chinese summary (i.e., the `summary` field contains only English text or is empty), generate:
+
+1. **summary** — A concise Chinese summary (1-2 sentences, starting with "本文"). Describe the core contribution and significance. Keep English terms (e.g., RAG, LLM, Transformer) as-is.
+2. **keywords** — 2-4 Chinese keywords. Keep well-known English acronyms as-is.
+3. **comment** — If the paper's venue is a well-known conference/journal, annotate its tier, e.g., "已发表在 AAAI（CCF-A）". Leave empty if unknown.
+
+Rules:
+- Do NOT fabricate information not present in the paper's title/abstract.
+- Do NOT generate or modify `famous_authors`.
+- If the abstract is missing or too short to summarize, write "摘要信息不足，请查看原文。"
+- Preserve all other fields unchanged.
+
+## Input
+
+The papers are in `papers_summarized.json` at the path provided. The file structure:
+
+```json
+{
+  "status": "success",
+  "profile_topics": ["topic1", "topic2"],
+  "papers": [
+    {
+      "title": "...",
+      "summary": "...(may be English-only)...",
+      "keywords": ["kw1", "kw2"],
+      "authors": ["..."],
+      "comment": "",
+      ...other fields preserved as-is...
+    }
+  ]
+}
+```
+
+## Output
+
+Write the enriched data back to the same `papers_summarized.json` path, preserving all fields. Only update `summary`, `keywords`, and `comment` for papers that need enrichment.